Project EPIC: Biobased coatings that biodegrade in the environment

Many paints, coatings and adhesives contain polyacrylates: polymers that act as binders, providing strength and durability. They are effective, but are hardly biodegradable in the environment. When small particles enter the environment through wear, weathering or flaking, they can remain there for a long time. This creates a difficult trade-off. A coating needs to last: a layer of paint that breaks down after a few months is clearly not fit for purpose. At the same time, we want to avoid materials remaining in the environment for years after use.

EPIC is therefore looking for a new balance: polymers that are strong and stable enough for their intended application, but that can break down under the right conditions. At the same time, the project aims to reduce dependence on fossil resources by developing biobased building blocks for these polymers.

The researchers are building on a relatively simple idea: facilitating biodegradation by adding more degradable linkages to the long polymer chain. Conventional polyacrylates consist of highly stable carbon-carbon bonds, which remain intact for a long time. By strategically introducing a different, more degradable bond, the researchers create weak points in the chain. In the environment, these bonds break down first, causing the long, highly stable chain to fall apart into smaller fragments. Micro-organisms can then break down these smaller fragments further.

The challenge lies in how these new, degradable building blocks are distributed: they need to be evenly spread throughout the polymer chain. The researchers are therefore developing ways to precisely control the order in which different monomers are incorporated into the chain during the production process, known as emulsion polymerisation.

At the same time, the project is working on another aspect of the design: the raw materials themselves. Many acrylates are still based on fossil resources. Wageningen scientists are therefore investigating how to develop biobased acrylates from renewable resources, including materials derived from agricultural waste.

The researchers have now produced the first polymers containing the desired biodegradable linkages. They are currently investigating whether these linkages are located in the right positions within the polymer chain. So far, they have produced relatively small quantities, measured in tens of grams. To prepare the materials for practical applications, the researchers are scaling up production to hundreds of grams and eventually kilograms. This will allow industrial partners to test the materials in their own laboratories. They will investigate, among other things, the robustness of the new polymers in different applications, such as paints, coatings and adhesives.

EPIC contributes to the transition of the chemical and materials industries from fossil to renewable resources. Biobased acrylates can reduce dependence on fossil resources, while the design of degradable polymer chains could help prevent residues from coatings and other products from accumulating in the environment over long periods.

For industry, the project offers new opportunities to better align the properties of coatings, paints and adhesives with their entire life cycle right from the design stage: strong and durable during use, but less persistent afterwards. The approach could also open up opportunities for recycling. The same linkages that promote degradation in the environment can also make it possible to chemically break down a coating in a controlled way at the end of its life.

EPIC brings together partners from different parts of the value chain. Wageningen University & Research is developing the new polymers and investigating their properties, while industrial partners are testing the materials in various applications. This means that the new polyacrylates are not only studied at the molecular level, but also assessed for how they perform as adhesives, coatings and paints when exposed to air and weather conditions over long periods.

The partners involved are Arkema, Stahl International BV, Baril Coatings BV, SABA Dinxperlo BV and Mirka Ltd. The project is supported by the Ministry of Agriculture, Fisheries, Food Security and Nature (LVVN) and Top Sector Agri & Food.